Tài liệu Answers - exercises w 5

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PART 3 PROGRAMMING CNC TURNING CENTERS OBJECTIVES: 1. Learn G-Codes associated with Turning Center Programming. 2. Learn M-Codes associated with Turning Center Programming. 3. Apply the proper use of feeds and speeds within Turning Center Programs. 4. Learn how to properly use coordinate systems for programming the Turning Center. 5. Learn program structure. 6. Learn how to properly use Multiple Repetitive Cycles. 7. Learn the mathematical method for offsetting tool path to compensate for the Tool Nose Radius. 8. Learn how to use Tool Nose Radius Compensation (G40, G41 and G42). 9. Emxamnie several practical examples of Turning Center programs. STUDY QUESTIONS 1. In NC (tape) controlled machines, the M02 command rewinds the tape to its start. How is a CNC machine commanded to return the program to its start? a. M03 b. M08 c. M30 d. M05 2. The tearm “modal commands” means that once the command is initiated it stays in effect until cancelled or replaced by another command from the same group? T or F 3. In programming, tool function is commanded by the four digits that follow the letter address T. (Emxample T040). What do these two sets of numbers refer to? The first two digits refer to the geometry offset and the second two are to the wear offset 4. Of the following choices, which is the best method for compensating for dimensional inaccuracies caused by tool deflection or wear? a. Geometry Offsets b. Wear Offsets c. Tool Length Offsets d. Absolute Position Register 5. When the rough turning cycle G71 is used, which letter identify the amount of stock to leave for finish for pass X axis and Z axis respectively? a. U and V b. X and Z c. P and Q d. U and W 6. Sequence (N) numbers in programs may be omitted entirely and the program will execute without any problem. T or F 7. The default (at machine start-up) feed rate on lathes is typically measured in: a. Cutting speed b. Inches per revolution in/rev c. Inches per Minute in/min d. Constant Surface Speed 8. The advantage of using G96 Constant Cutting Speed in turning is that as the diameter changes (positon of the tool changes in relation to the centerline) the r/min increases or decreases to accomplish the programmed cutting speed? T or F 9. The preparatory funtion G50 relates to two things in programming: a. Absolute positioning setting and maximum spindle r/min setting. b. Absolute position setting and constant spindle r/min. c. Work offset and tool offsets d. Absolute position setting and Constant Surface Speed. 10. When incremental programming is required in turning diameters and facing, which letters identify the axis movements respectively? a. I and J b. U and W c. I and K d. U and V 11. Which M-Codes are used to activate and deactivate a subprogram respectively? a. M03 and M04 c. M98 and M99 b. M02 and M30 d. M41 and M42 12. What M-Code is listed in the last line of a subprogram? a. M30 c. M98 b. M99 d. M02 13. What two letters identify the incremental distance from the starting point to the arcs center in G02/G03 programming? a. I and J b. I and K c. J and K d. X and R 14. When programming arcs with modern CNC contrllers I, J and K can be omitted and replaced by R. If the arc is greater than 1800, what must be added to the R command? A negative sign 15. Fixed cutting cycle G90 is limited to orthogonal tool movements (no contouring or chamfers are allowed) T or F 16. When using the Multiple Repetitive Cycle, Rough Cutting Cycle, G71, U and W represent the stock allowance for finishing. What cycle is required to remove the stock allowance? a. G90 b. G73 c. G76 d. G70 17. What is the major reason for selection of the Pattern Repeating Cycle, G73 as opposed to the Rough Cutting Cycle, G71? a. It is required to make the finish allowance cut on X and Z. b. This cycle is well suited where an equal amount of material is to be removed from all surfaces. c. G73 is limited to orthogonal cuts while G71 can cut radius and chamfers. d. G71 is limited to rough cutting only while G73 is required to remove stock allowances. 18. When programming arc and angular cuts using tool nose radis compensation, G41 and G42, which is used for facing and turning when the tool is mounted above the part centerline. a. G41 facing, G42 turning b. G42 facing, G 41 turning c. Neither, the tool nose radius amount must be calculated and programmed to compensate. d. G41 for facing if contours or angles are involved, G42 for turning if contours or angles are involved. 19. Tool tip orientation needs to be identified in the controller when TNRC is used to program functions G41 or G42. How is this information input? a. The number is input by R into the prgram. b. The number is input by T into the offset page. c. The number is input by R into the offset page. d. The number is input by T into the prgram. 20. Using the tool figures 89, 91 95 and 96. Identify the tool tip identification numbers. 21. When programming the G76 multiple thread cutting cycle, the letter address I allows for programming: a. Tapered thread cutting b. Elimination of taper in thread cutting c. Both a and b d. a only 22. Name one reason that writing programs using Tool Nose Radius Compensation (TNRC) is advantageous.
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